Production of 2,2,4-trimethyl-3-hydroxypentanal

ABSTRACT

Production of 2,2,4-trimethyl-3-hydroxypentanal by dimerization of isobutyraldehyde in the presence of a basic ion exchanger. The product is a valuable intermediate for the production of polyesters and plasticizers.

ilnied States Patent Merger et ai. 5] June 27, 1972 541 PRODUCTION OF2,2,4-TRINmTHYL-3- 3,077,500 2/1963 Heinz et a1. ..260/602 xHYDRQXYPENTANAL v 2,863,878 12/1958 Lynn ..260/602 [72] Inventors: FranzMerger, 8 Homburger Strasse, 6700 OTHER PUBLICATIONS Ludwlgshafeni T 5Hansastrasse Durr,G., Ann. de Chim., v01. 13,pages 85-114,1956. 6800Mannheim; Erich Nebe, 145 Rohrit n Hagemeyer et al., The Chem. oflsobutyraldehyde etc., bacher Strasse, 6900 He1delberg, all of 1953,page 17. Germany [22] Filed: Dec. 27, 1968 Primary Examiner-Leon ZitverAssistant Examiner-R. H. Liles PP NM 787,610 Attorney-Marni], Johnston,Cook&Root

[52] us. Cl ..260/602 [571 ABSTRACT Field of Search ..260/ 602References Cited UNITED STATES PATENTS Production of2,2,4-trimethyl-3-hydroxypentanal by dimerization of isobutyraldehyde inthe presence of a basic ion exchanger. The product is a valuableintermediate for the production of polyesters and plasticizers.

6 Claims, N0 Drawings PRODUCTION OF 2,2,4-TRlMETHYL-3- HYDROXYPENTANALThe invention relates to the production of 2,2,4-trimethyl-3-hydroxypentanal by dimerization of isobutyraldehyde in the presence ofbasic ion exchangers.

It is known that isobutyraldehyde can be cyclized in the presence ofalkali or amines at from 5 to C to 2,6-diisopropyl-S,S-dimethyl-1,3-dioxanol-(4). The reaction is reversible at60 to 70 C in the presence of an alkaline catalyst (Hagemeyer, TheChemistry of isobutyraldehyde," Tennessee Eastman Company). The saiddioxanol derivative can be split up with dilute mineral acid oraliphatic carboxylic acids into isobutyraldehyde and2,2,4-trimethyl-3-hydroxypentanal. (isobutyraldol) (loc. cit.; US. Pat.specification No.2,829,l69). Distillation of the dioxanol derivativeonly gives a clear formation of isobutyraldol when acid is added (Ber.,76, 1199 (1943)). An article in Am. Soc., 65, 1716 teaches that thecrude product of the action of alkaline solutions on isobutyraldehydeunder mild conditions does not contain any aldol but is present in theform of the dioxanol deriva' tive.

It is known from German Pat. printed application No.1,235,883 thatisobutyraldehyde and formaldehyde can be reacted at 85 to 100 C in thepresence of basic ion exchangers to form 2,2-dimethyI-B-hydroxypropanol.isobutyraldol is not obtained.

The object of this invention is to produce 2,2,4-trimethyl-3-hydroxypentanal in good yields and high purity by a simple one-stagemethod.

This and other objects of the invention are achieved and2,2,4-trimethyl-3-hydroxypentanal is obtained advantageously bydimerizing isobutyraldehyde in the presence of a basic ion exchanger ata temperature offrom 35 to 80 C.

The dimerization may be represented by the following equation:

Having regard to the state of the art it is surprising that 2,2,4-trimethyl-3-hydroxypentanal should be obtained in good yields and purityin a simple step. There is no appreciable formation of byproducts, forexample 2,6-diisopropyl-5,5- dimethyl-l ,3-dioxanol-(4).

Dimerization of the starting material (isobutyraldehyde) is carried outin the presence of ion exchangers having low, medium or preferably highbasicity, or mixtures of the same. A number of basic ion exchangerswhich can be used for the process is given in HoubenWeyl, Methoden derOrganischen Chemie," volume l/l, page 529, "Anion exchangers. It ispreferred to use strongly basic ion exchangers having tetraalkylammoniumor trialkylhydroxyalkylammonium groups. It is advantageous to choose anexchanger in the carbonate form or to bring it into this form prior tothe reaction, for example by treatment of an exchanger in the chlorideform with sodium carbonate solution; the reaction may however be carriedout with the hydroxide form of the exchanger. The form and particle sizeof the exchanger may be chosen at will within a wide range. In batchwiseoperation, for example in a stirred vessel, the exchanger is generallyused in an amount of from 10 to 100 percent, preferably from to 50percent, by volume with reference to starting material. The process mayalso be carried out continuously for example by passing isobutyraldehydethrough exchanger columns (ratio of length to diameter, for example10:!) and generally 1 to 10 percent by volume of exchanger is used withreference to the average amount of aldehyde passed through the exchangerper hour. To avoid dehydration and shrinkage of the exchanger resin,particularly in continuous operation, the addition of for example 2 to10 percent by weight of water with reference to the isobutyraldehyde isoccasionally advantageous. The exchanger can be reactivated after thereaction in the usual way, for example by treatment with aqueous sodiumcarbonate solution followed by rinsing with water, and may be reused inmoist or dry condition. The exchangers have a long life; no loss inactivity can be detected after reaction lasting 100 hours. Informationconcerning the production and details regarding use of ion exchangersmay be found in the chapter on Ion exchangers" in volume V l ofl-louben-Weyl referred to above.

The reaction is carried out at a temperature of from 35 to C, preferablyfrom 50 to 70 C, at atmospheric or superatmospheric pressure. It isadvantageous to carry out the reaction in the presence of gases whichare inert under the reaction conditions, for example nitrogen, in orderto avoid loss in yield and deactivation of the exchanger by oxidation ofisobutyraldehyde and isobutyraldol.

The reaction can be carried out as follows: isobutyraldehyde and basicion exchanger are kept in a stirred vessel under nitrogen at thereaction temperature for from 1 to 20 hours, particularly from 5 to 12hours. The reaction mixture is then filtered and isobutyraldol isseparated from the filtrate by fractional distillation.

The compound which can be prepared by the process according to thisinvention is a valuable intermediate for the production of2,2,4-trimethylpentanediol-( 1,3) which can be processed into valuablepolyesters and plasticizers (see An Eastman Chemical Product,2,2,4-trimethyl-l,3-pentanediol, Properties and Applications," 1964,Eastman Kodak Co.)

The invention is illustrated by the following examples. The partsspecified in the examples are by weight unless otherwise stated; theybear the same relation to parts by volume as the kilogram to the liter.

EXAMPLE 1 1,000 parts of isobutyraldehyde is stirred in a stirred vesselin the presence of 400 parts by volume oftrialkylhydroxyalkylammoniumpolystyrene in the carbonate form for 10hours under nitrogen and boiled under reflux. The temperature of thereaction mixture rises from 60 to 70 C. The isobutyraldol formed isidentified by thin layer chromatography (R O, 6, silica gel G,benzene/acetone :10). After the exchanger has been filtered ofi', themixture is distilled over a fractionation column. 370 parts of unreactedisobutyraldehyde is recovered and 570 parts of isobutyraldol having aboiling point at 12 mm of from 88 to 90 C is obtained. This isequivalent to a yield of 90.5 percent of the theory with reference toreacted isobutyraldehyde.

EXAMPLE 2 1,000 parts of isobutyraldehyde is stirred in the presence of350 parts by volume of tetraalkylammoniumpolystyrene in the carbonateform in a stirred vessel for 8 hours under nitrogen and boiled underreflux. The temperature of the reaction mixture rises from 60 to 80 C.After the exchanger has been filtered off, the mixture is distilled overa fractionating column and (in addition to 445 parts ofisobutyraldehyde) 485 parts of isobutyraldol having a boiling point offrom 88 to 90 C at 12 mm is obtained, equivalent to 87.4 percent of thetheory with reference to isobutyraldehyde reacted.

We claim:

1. A process for the production of 2,2,4-trimethyl-3-hydroxypentanalwhich comprises contacting isobutyraldehyde with a basic ion exchangerat a temperature of from 35 to 80 C. and obtaining the2,2-4-trimethyl-3-hydroxypentanal product by distillation.

2. A process as claimed in claim 1 wherein the isobutyraldehyde iscontacted with a strongly basic ion exchanger containingtetraalkylammonium groups.

3. A process as claimed in claim 1 wherein the reaction is carried outbatchwise using the exchanger in an amount of from 10 to percent byvolume with reference to starting material.

4. A process as claimed in claim 1 wherein the reaction is carried outbatchwise in the presence of an exchanger in an amount of from 25 to 50percent by volume with reference to starting material.

5. A process as claimed in claim 1 wherein the reaction is carried outcontinuously in the presence of from 1 to percent by volume of exchangerwith reference to the average 5 amount of aldehyde passed through theexchanger per hour.

6. A process as claimed in claim 1 wherein the reaction is carried outat a temperature offrom 50 to 70 C.

33 3 nnnnn STATES PATENT orwen @ERHHQA'EE m QQRREQHQN Patent No.3,673,258 Dated June 27', 1972 Inventor(s) Franz Merger, Rolf Platz, andErich Nebe It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Fir-st age, left-hand column, under "Germany" insert [75 Assignee: IBadische-Anilin- 8c Soda-Fabrik Aktiengesellschaft, Ludwigshafen/Rhein,Germany First page, left-hand column, 'under' Appl. No. 787,610" insert[3@ Foreign Application Priority Data 7 December 29, 1967 Germany. .P 1643 727.7

Signed and sealed this 19th day of December 1972.

(SEAL) Attest:

EDWARD MELETCHERJR. ROBERT GOT'ISCHALK Attesting Officer Commissioner ofPatents

2. A process as claimed in claim 1 wherein the isobutyraldehyde iscontacted with a strongly basic ion exchanger containingtetraalkylammonium groups.
 3. A process as claimed in claim 1 whereinthe reaction is carried out batchwise using the exchanger in an amountof from 10 to 100 percent by volume with reference to starting material.4. A process as claimed in claim 1 wherein the reaction is carried outbatchwise in the presence of an exchanger in an amount of from 25 to 50percent by volume with reference to starting material.
 5. A process asclaimed in claim 1 wherein the reaction is carried out continuously inthe presence of from 1 to 10 percent by volume of exchanger withreference to the average amount of aldehyde passed through the exchangerper hour.
 6. A process as claimed in claim 1 wherein the reaction iscarried out at a temperature of from 50* to 70* C.